Telephone system



2 Sheets-Sheet l J. WlcKs TELEPHONE sYsTEM Filed.' June so, 1959 u n m55 IHJQQ w@ @E @SQ EE mi IJ www@ @S March 3, 1942.

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March 3, 1942. J, WlcKs TELEPHONE SYSTEM Filed June 30, 1939 2 Sheets-Sheet 2 @mm @Su m 0mm mm w A vPES5/J. ml.' mz3 ?.tgmfj B mw www? E @Indi mz3 @GND NW9@ r @www V l w R2@ @S www5 L mwm @QB l '.4 m L1 S w n lp lilo Al :Em :ESG omdm All m23 FJN`N` v 4 QN .T LI l nnnm. A| notam KJ@ .UAI I.. mzzou 1. Al T1 JQ MLI|IQIIQA| :Em f5@ f Al m Stam Al umzzoo EommfJ.\. mz3 lll JOHN WICKS BY ATTORNEY 5.

Patented Mar. 3, 1942 UNITED S PATENT, i ortie l2,274,760 TELEPHONE SYSTEM John Wicks, Oak' Park, Ill., assigner to Associated Electric Laboratories, Inc.,QChicago, Ill., a corporation of Delaware Application June 30, 1939, Serial No. 282,007

23 ciaims. (el. 179-18) The present invention relates to automaticl tions to forward calls incoming to the line through the automatic switching apparatus embodied in the exchange to another line of the system. 'Ihe call forwarding apparatus has embodied therein a register whichmay be set Vso that the call forwarding apparatus' will function to forward the calls to any desired subscribers line of the system. In order to set the register'l` substation to which the calls are to be forwarded. The particular arrangement disclosed requires a large amount of complicated equipment in order to obtain the desired end. Moreover, each substation for whichy call forwarding service is to be provided must be equipped with a special dial or calling device capable of transmitting twelve impulses therefrom. In addition, certain of the first selector switches of the system must be specially designed so that they are capable of operating twelve steps in a vertical direction. Further, the arrangement is such that the register embodied in the call forwarding apparatus can only be set from the particular substation which the apparatus is arranged to serve. y

It is an object of the present invention, therefore, to provide in an automatic telephone system, improved call forwarding apparatus'of the general character described which is simple in arrangement, is economical to manufacture and install, and is thoroughly reliable in operation.

It is another object of the invention to provide in an automatic telephone system, improved call forwarding apparatus of the character described which is so arranged that it may be conditioned for operation overy any line of the system.

It is a further object of the invention to provide in an automatic telephone system, improved call forwarding apparatus of the character described wherein the apparatus may be set to for- Ward calls incoming to the associated line to any desired one of a number of substations by transmitting thereto a single digitof impulses.

It is a still further object of .the invention to provide improved'call forwarding apparatus of the character described which is adapted for use in 'an automatic telephone system employing practically any of the well-known types` of automatic switchingapparatus without in any way necessitating modification of the installed equipment.

The invention is illustrated in its embodiment in an automatic telephone system which comprises a plurality of subscribers lines extending to a line terminating exchange'and automatic switching equipment provided in the exchange-k for setting up connections between the llines.

Briefly described, the call forwarding apparatus comprises a register, means controllable over any line of the system for variably setting the register in accordance with the directory designationof another of the subscribers lines, and apparatus operative when a call is directed to the subscribers line arranged for call forwarding service, under the condition of the register being set, for causing the call toberouted to the one of the other lines of the systems which corresponds to the setting of the register. More `particularly, the call forwarding apparatus ccmprises an impulse sender for directively controlling the automatic switchingl apparatus to forward 'calls incoming to the associated line toa selected one of the other lines, and an impulse responsive switch for selecting-the one of the other lines to which the calls are to be forwarded and to control` the operation of the impulse sender in accordance with the line selected. The apparatus further comprises control means operative to initiate the operation of the impulse sender and a control circuit which is adapted Ato be seized over a connection routed through the automatic switching apparatus from any' line of the system. This circuit includes means for repeating to the impulse responsive line; selecting switch impulses transmitted over the connection extending to the circuit, thereby to cause the impulse responsive switch toselect the one of the lines to which the calls are to be forwarded. The control circuit further comprises means for conditioning the above-mentioned control means to operate in response to a call routed to the line associated with the call 'forwarding apparatus. The arrangement is such that if a connection is routed to the control circuit after the call forwardingk apparatus has been conditioned for operation and is then released, the impulse responn sive line selecting switch embodied in the apparatus is released and the control means for initiating the operation of the apparatus is rendered nonresponsive to calls routed vto the associated line. There is further provided an arrangement, operative when the` control circuit is I seized,'for transmitting a signal of one characspond to calls incoming tothe 'associatedline.

Further features of the invention pertain to the particular arrangement ofy the circuit` elements whereby the above and additional operating features are attained.

The novel features believed to be characteristic of the invention aresetiforthiwith particularity in the appended claims. The invention, both as to its organization'and method` of operation, together with further objects and yadvantages switches are of the well-known Strowger type, each having embodied therein a Strowger switching mechanism utilizing vertical and rotary motions in the operation thereof to sel-ect an outgoing line. Obviously, the control apparatus embodied in the selector and connector switches is different in each case depending upon the character of the switch. In this regard it is. pointed out that the control circuit Z, through operation of which control of the call lforwarding apparatus is effected, may be rendered accessible to the selector switches of the system by terminating .the..'conductors of the link line extending thereof will-'best be understood by reference to 25.

the specification taken in connection with the accompanying drawings in which Figures 1V and 2 illustrate an automatic.I telephone system having incorporated therein" call forwarding apparatus and control apparatus constructed and ar- 3o ranged in accordance with the present invention, and Fig. 3 illustrates amodification oi the apparatus which may. be provided for controlling the call forwarding apparatus.

.theretoin the first set of contacts of a dead conta"ct"level,rr thatisthe nrst set of contacts to be engagedfb'y the wipers of the respective switches during rotary movement thereof when the wipers are vertically` positioned opposite the level containing -the inactive contacts.

Neglecting for the present the particular arrangement of the call forwarding apparatus and' the control 'circuit therefor, the system as described above is entirely conventional in form and its" mode ofr operationis Well `understood in the art. Briefly described, if a subscriber at the substation A, for example, initiates. ya call intended for the substation B; by removing the receiverv providedV at the substation .A1-from its supporting` hook or cradle, a calling loop circuit is completed by way of the line i0 forinitiating the'v operation of thel` line switch I3. switch responds to the-completion of the calling Vloop` circuit by operating. to lselect a trunk line Briefly described, the: system illustrated inthe 351 ing apparatus provided in` the line terminating 401i:

exchange. This apparatus' comprises line switches I3, i4 and I5" individually associated with the lines l, II and I2, a-pluralityfofvimpulse responsive selector switches. includingv 'the' two switches indicated at4 I6 and Il', andaiplurality of .impulse responsive connector switches,`two of which are indicated at I8 and I9, respectively. The system further comprises-call forwarding apparatus illustrated infdetail inFig. 1v which is individual to the substation A. In order to control this apparatus there is provided a control circuit 20 which is accessible to each of the first selector` lswitches embodied in the line terminating exchange. The arrangement of the call forwarding apparatus as provided in conjunction with the substation A, is such thata repeatingY coil |60, alink line 2I and a line switch ZZindi'vidual to the line 2l are utilized in forwarding calls incoming to the line I to another line of the system, which other line is predetermined in` accordance with the setting ofthe call forwarding'apparatus.

'Ihe line switches I3, I-l,V I5' and'22 are commonly known as non-numerical switches for the. reason that they perform no liner selectingoperations other than the selection of trunk lines extending to idle ones of the rst selector'switches. Preferably, these line switches arevof the well-` known rotary type of which several commerciall embodiments are available. The selector and connector switches of the systemare commonlyy known as numerical `switches for the reason that they are directively controllable in accordance with impulses transmitted thereto to performrline group, subgroup and particularv line `selecting operations.

is f

roi

extending to an idle one of the first' selector switches.; If the selector switch I5 is the iirst available idley selector switch accessible to the.

line switch I3, the last-mentioned-switch, upon testing the condition of the trunk lineextending to the selector switch IS--and'nding this linezto beidle,` operatesy to extend th'e calling loop circuit to the indicated selector switch, `In response to.

this-operation, thecontrolfapparatus of the'selector switch I6 functions in a well-known manner to transmit the usual dial -tone signal over the calling line,`thereby to inform the-calling-subscriber that thedialing operation may be started.

The'selector switch. lresponds to the impulses of the Afirst digit dialed at the calling substation A by elevating its wipers to a position opposite the level of baril; contacts-terminating the trunk lines respectively` extending` to the connector` digit'pau'se'betwe'en' thefirst and second digita' the wipers of the selector switch I5 are rotated step4 by stepv in' the'usua`l1n'1anner successively' to test then condition ofthe trunk' lines respectively' extending tothe [connector switches ofL the` selected group. -If'the' connector switch* I8 is the first available idle-*switch of' the selectedv groupytherotarymovement of the *wipersl ern-V bodied in the selector switch IS"1 is arrested when theseE wipers engage the contacts terminating theV conductors of'the trunk line-incoming tothe indicated connector switch. lFurthen--the controlv apparatus of theselector switchy If functions to' extend the calling loop circuit to-the seizedy connector switch I-8, whereby the' control appara-tus of the latter switch is conditioned., to respondto' the impulses of the' second digitv dialedY at the Preferably,v the "last-"mentioned 7151 calling substation;` During the' dialing -of the This line second digit, the wipers of the connector switch I8 are elevated step by step in a Vertical direction to a position opposite the level of bank contacts terminating the group of ten lines including the called line In response to the impulses of the third digit dialed at the calling substation,

these wipers are rotated into engagement with the particular set of bank contacts at which the conductors of the line Il are terminated. Following the selection of the called line in the manner just explained, the control apparatus embodied in the connector switch I8 functions to determine the idle or busy condition of the selected line and to transmit the usual busy signal over the calling loop circuit to the calling subscriber in the event the called line is busy. If the called line is found to be idle, the control equipment embodied in the connector switch i8 functions to transmit ringing current over the called line for the purpose of energizing the ringer or signal device conventionally provided at the called substation B. This equipment further operates to transmit a portion of the ringing current back over the calling loop circuit, whereby the usual ring-back tone signal is reproduced by the receiver provided at the calling substation. When the call is answered at the called substation, a direct current bridge is connected across the conductors of the line l, thereby to complete, in the usual manner, a direct current circuit for energizing the ring cut-off relay conventionally embodied inthe control equipment of the operated connector switch. This relay, upon operating, functions to terminate the ringing operation, to terminate the ring-back tone signal, to extend the loop circuit originating at the called substation through the windings of the back bridge or battery reversing relay embodied in the connector switch, and to complete the desired conversational circuit between the calling and called substations. The indicated back bridge relay, upon operating, functions to reverse the direction of current flow over the loop circuit extending to the calling substation in a manner well understood in the art. This reversal of current iiow over the calling loop circuit may be utilizedfor control purposes, such, for example, as call metering, or the like. The manner in which the connection is released depends upon the particular arrangement of the control apparatus embodied in the connector switch I8. For example, this ap-paratus may .be so arranged that the operated switch train is released only when the connection is cleared out at both the calling and called substations. Alternatively, the control apparatus of the connector switch I8 may be so arranged that the release of the switch train is entirely under the control of the calling subscriber. Assuming that the latter arrangement is employ-ed, when the calling party replaces the receiver provided at the calling substation upon its supporting hook or cradle, the calling loop circuit is interrupted with the result that the connector switch I8, the selector switch I6 and the line switch I3 are released in the order named and in a manner well understood in the art. When these switches are all restored to normal, the calling and called lines I0 and ll, respectively, are marked as idle in the bank contacts of the connector switches having access thereto, and the apparatus utilized in completing the connection is rendered available for further use. In view of the foregoingV brief description, it is believed that the manner in which connections may be established between apparent without further explanation.

Referring now more particularly to the arrangement of the call forwarding apparatus illus- `trated in Fig. l and individually associated with the substation A, this apparatus comprises a register which includes an impulse responsive line selecting switch |65, an impulse counting or sending control switch |80, a digit sequence switch |85 and an impulse sender comprising a relay R|25 having a weighted armature |26 which is adapted to vibrate at a rate of approximately ten vibrations per second. The apparatus further comprises a first timing device in the form of a vibratory relay Rlllll which is operative in conjunction with a slow-to-release relay R|05 to delay the operation of the register for a predetermined time interval after a call is routed to the line lil. There is'also provided a second timing device in the form of a vibratory relay RI l5 which, in combination with a second slowizo-release relay Rlil, functions to delay the release of a connection through which a call is forwarded for a predetermined time interval after the connection is set up. A third timing device in the form of a vibratory relay R|33 vis provided, which, in conjunction with a slow-to-release relay RHS, functions to insure the complete release of a switch train through which a call is' forwarded before a second cycle of operation of the register is started. The call forwarding apparatus further comprises a plurality of additional control relays'including the relay RMS for operatively associating the apparatus to respond to calls incoming to the line It, an alternating current relay R|5|l which is operative to initiate the operation of the apparatus in response to ringing current transmitted over the line Ill, a slow-to-release relay RH il which is controlled by the two relays RMS and RIM and is operative of ten points each; three wipers ll'i to |13, in-

elusive, individually associated with the contact sets in the order of enumeration, means comprising an operating magnet |76 and a ratchet and pawl mechanism, not shown, for driving the enumerated wipers over the contacts of their respective associated contact sets and two sets of oi-normal springs |13 and |79, which are provided for control purposes described hereinafter. The impulse counting or sending control switch |8 and the digit sequence switch |85 are of the means comprising a motor magnet |81 and av ratchet and pawl mechanism, not shown, for

the other substations of the system will be clearly acca-.780i

driving the awiper.: H30 over. `the :contacts ,.ofz. the

associated Contact'. setand'ra 'lrelease magnet il 80- which iis :operative tto :cause "the wiper i186 @tofbe returnedto its home position.;V

As :indicated .previously;. the .call l forwarding;

apparatus just described: isiarranged. to be controlled :by: the. apparatus: embodied .inl .the icone trol circuitl .2 0, which. controlcircuit is :accessibleto eachf`of the rst selectorlswitches:ofithe"sysev tem.:v Briefly; described: the control 'circuit 20 comprises aline. relay.R2I, a slow-to-release hold relay R220,l acontrol relay R230, a slow-torelease impulse responsive'relay'R240 land a call sequence relay network. comprising the two relays R259v and. R260, This control circuit has associatedtherewith twosources of alternating..

currents having diiierent signaling characteristics; the current of one source beingutilized in signalingover an established connection extending to the controlcircuit 20,'. that the callfo'rwarding apparatusis conditioned to respond to calls incoming to the line I0, and the .current of the other source .being utilized in signaling over an. established connection extending to the control. circuit. 20 thatv the call forwarding apparatus is not operativelyassociated with the.

line I0.

Referring now more particularly to the opera.- tion of the control circuit 20: and the call for. warding apparatus illustrated in Fig. 1, it will be apparent that with the. start relay RI45 deenergized such that .the repeating coil IED' is .disconnected from the line I0, callsmay be `routed to and from the substation A without interference occasioned by the associated call forwarding apparatus and Without in any way initiating the operation of this apparatus. Further; if the relay RI45 is operated such that the callforwarding apparatus is conditioned for operation, calls originating at the substation A may successfully be complet-ed without. interference occasioned by the call forwarding apparatus and, in addition, calls incoming to this substation may be answered at the substation even though operation of vthe call forwarding .1 apparatus is. initiated..

As indicated in the introductory portion of the` specification, the call forwarding apparatus may be conditioned to respond to calls incorningto.y

the line I by controlling the circuit 20 over any line of the system. For example,if the .subscriber for whose service the substation VA is provided .is temporarily located at the substation Banddesires that calls routed to the substationA Abe iorwarded at the substation B, he may conditionthe call forwardingapparatus to forward'calls to they substation B by initiating a call at the substation B and dialing a directory number of two digits` When ,the call is initiated at. thesubstation B, the line switch I4 operates td select lan idle one ofthe selector switches to which it hasaccess. Assuming that the selector switch I6 is seized and, further, that the link line t'extending to' the control circuit 20 is. terminated in the 'first contact 'set of the tenth level in each of the iirst.

selector switches, the calling party'upon initiat` ing the call and receiving the usual dialtone signal dia-ls a rst digit of ten impulses, causing the wipers of the selector switch I6 to be operatedto a position opposite the tenthA level Iof contacts.

During the interdigit pause between the first and I second digits, these wipers are rotatedto engagel the contacts terminating the conductors of. the.. link yline 25. In response to this operation,` the linefrelay R2 I0 `is energized'cver the .callingloopf circuitl .and operates. :to :completal at RAZ I? I, an175Cdetermining,'.ployfitsy :cross'-:connectionrto one :.of..

obvious.; circuitv `for impressingfground potential upon; the control-y conductor .of .the :linkfline e255. thereby; to :maintain Athe :selector switch "I 6 operatedv in 'the usual manner. When'the link linef25 is seized'by the .selector switch IB; acircuit is completed `for transmitting. over the calling loop:

circuit a signal current which, when reproduced,y

informs the calling party that the call forwarding apparatus is at normal. The path traversed by this current may be traced as extending; from one terminal of the signal current source by way of C256, RA254, the condenser 364, one sidenof the calling loop circuit, the receiver at the calling substation,.the otherside'of` the calling loopgcirsignal current source.

path extending .through RAI forimpressing.V groimdrpotential upon the .control :conductor of the linkline 25.Y At RA222,"the relay R220'prepares a circuit for energizingA the relay R240 in 25. series with the operating magnet |15. At RA223,

the relay R220 completes-:a circuit `extending by way of CISS for energizingthe start relay RI45." At RA224, thevrelay R220 completes a .circuit forl energizing the impulse .sending relay RI25,:' this cscircuit extending from .ground by way of RA224,\.

CI98,.RAI23 and the winding Iof R125 vto battery.` When energized over this circuit, the relay RI-25 attracts itsweighted armature |26 'thus conditioning this armature for vibrationH when 'the uoperating circuit just traced is .subsequently in peater-windings vI6! and '|62 tothe conductorsA cf the line I0, thereby to condition the-alternating current relay R150 to respond to ringing cur- L L5- rent transmitted over the indicated' line. At

'RA|.48,'the relay R145 :prepares acircuit traced hereinafter for energizing the Yslovxr-Jto-'release re'. lay 'RI l0.' The relayRlUOyupon operating; at'.-

tracts its YWeighted 'armature'RAIIlI` 'to complete l' `an obvious circuit for energizing the slow-tof-re'- lease relay'Rl05. The relay'RIf05,.upon operating, opens, at RAI 08,:a pointA inthe circuit tracedy hereinafter for .energizing the release magnet |88.'

AtJzRAI 01, the` relay `RI 051'opens :a point 'in` the icperatingcircuit for'` the relayfRI I5.v At R'AIUB,

therelayR'IlE"prepares alholding circuitfor the'relay Rl I0. Fllowing;the operation of the relays `R2I0, R220, R`I45,` RI00,'1RI05"and"RI25; the..ca11 forwarding .apparatus andthe control circuit 2G are'conditioned to .respond to theim'- y'pulses of the second digitdialed at the substa-l tionB. The numericalv value of this second digit determines the substation .to :whichfcalls incorn. ing to the line I0 .will.be.forwarded.. Thus, each .65 verticalrow of ibank"contacts. embodied 'in'fthe line. selecting switch I'corresponds to a par# tic'ularA one ofv .thefsubstations the contact' ofi eachvertical row whichz is .include'd'in thecon;

tactfset 168 determining, by its cross connection toene-of fthecontactsof the impulse counting switch. |",J=the number ofiimpulses ofthefrst digit of the directory number designating .the cor.-`

responding substationy the contact "of 'the .same verticali row. and included :in the contact, setlll 6T the contacts of the impulse counting switch |80,

the number of impulses of the second digit; and the contact of the same vertical row included in the contact set |65 determining, by its cross connection to one of the contacts of the impulse counting switch |80, the number of impulses of the third digit. For example, if the second vertical row of contacts in the switch corresponds to the substation B and the directory number of this substation is 324, the connections illustrated in Fig. 1 of the drawings may be used. More particularly, the second contact of the contact set |58 is connected to the third contact of the contact set embodied in the switch |80; the second contact of the contact set |61 is connected to the second contact of the contact set embodied in the switch |80; and the second contact of the set |66 is connected to the fourth contact of the contact set embodied in the switch |80. It will be clearly apparent that the other vertical rows of contacts embodied in the contact bank of the switch |65 and individually corresponding to other substations to which calls may be forwarded are cross connected to the bank contacts of the switch |80 in diierent manners depending upon the numerical Values of the digits of the directory numbers designating the respective corresponding substations. It will also be apparent that by increasing the number of contact sets in the line selecting switch |65, the register may be arranged to transmit more than three trains of impulses during each call forwarding operation. In view ofthe irnrnediate preceding explanation, it will be understood that in order to cause calls incoming to f the line I0 to :be forwarded to the substation B,

the wipers III to I73inclusive, of the switch |65 must be positioned upon their respective associated second contacts. To this end, a second digit of two impulses is dialed at the calling substation B. At the beginning of the open circuit period oi' the first impulse of this digit, the line relay R2| 0 restores to open, at RA2| I, the initially completed path for impressing ground potential upon the control conductor of the link line 25. At RA2|2 and its associated working contact, the relay R2|0 opens the operating circuit for the relay R220. The latter relay, due to its slow-to-releas'e characteristic, remains operated during impulsing. At RA2|2 and its associated resting contact, the relay R2|0 completes the previously mentioned circuit for energizing the slow-to-release relay R240 in series with the winding of the operating magnet |16, this circuit extending from ground by way of RAZ I 2, RA222, RAZSI, the winding of R240, C|54 and the winding of the magnet |16 to battery. When energized over this circuit, the relay R240 immediately operates to open, at RA24I, a point in the circuit traced hereinafter for energizing the control relay R230. Due to its slow-to-release characteristic, the relay R240 remains operated during the impulses ofthe impulse train transmitted to the control circuit 20 and only releases shortly following the end of this impulse train. At the end of the open circuit period of the rst irnpulse, the relay R2|0 reoperates to recomplete the operating circuit for the hold relay R220, to recomplete, at RA2I I, the path for impressing ground potential upon the private conductor of the link line 25, and to interrupt the above-traced pawl mechanism, functions to advance the wipers |1| to |13, inclusive, one step from normal andv into engagement with their respective associated first contacts. When these wipers are stepped to the rst ofi-normal position, the off-normal n springs |18 aremoved into engagement to prepare a circuit traced hereinafter -for energizing the magnet |10 during the release of the apparatus. The off-normal springs |19 are also moved into engagement in response to operation of the wipers |1| to |13, inclusive, to the rst off-normal position. When these latter `oir-normal springs are-engaged, acircuit is prepared for energizing the control relay 230. The line relay R2|0 functions to repeat the additional impulses of the second digit to the operating magnet |15 of the switch |05 in the exact manner just described with reference toA the rst impulse of this digit. Since the wipers |1| to |13, inclusive, are stepped at the rate of one step for each impulse, itwill be apparent that in the case under consideration wherein asecond digit'of only two impulses is Ydialed at the substation B these Wipers are left standing in engagement with their respective associated second contacts, which contacts correspond to the substation B.

At the end of the second digit, the line relay is held energized Aover the calling loopV circuit until the connection is released at the substation B. With this relay operated, the abovetraced circuit serially including the winding of the relay R240 and the winding of the magnet |16 is opened. Accordingly, the relay R240 restores shortly following the end of the digit to complete the above-mentioned circuit for energizing the control relay R230, this circuit extending fromground by way of the off-normal springs |19, RA24| and the winding of R230 to battery. When energizedv over this circuit, the

relay R230 operates to open, at RA23I and its associated resting contact, a further point in the circuit for energizing the relay R240 and the magnet |16 in series. At RA23I and its associated working contact, the relay R230 prepares a circuit for energizing the relay R250. At RA232, the relay R230 completes a holding circuit for the hold relay R220, this circuit extending from ground by way of RA202, RA232 and the winding of R220 to battery.

After dialing the twov digits requiredto condition the call forwarding apparatus for operation and to select the substation to which calls incoming to the line I0 are-to be forwarded,

` trol conductor of the link line 25. At RA2|2 and circuit for energizing the relay R240 and theoperating magnet |16 in series. When energized in cooperation with its associated' ratchet and its associated working contact, the relay R2|0 interrupts the operating circuit for the relay R220. At RA2|2 and its associated resting contact, the relay R2|0completes the above-mentioned circuit for energizing the relay R250, this circuit extending from ground'by way of RA2l2, RA222, RA23I, RA26| and the winding of R250 to battery. Upon operating, the relay R250 completes, at RAZ 52, a path for short-circuiting the winding of R260, this path extending from.

ground by way of the off-normal springs |19,

RAZSL the- Winding ofIRZBWRAZGLTRAZBL the relay R255, uponoperating, interrupts the `previously traced alternative `path over'which ground potential is impressed upon the lcontrol conductor of the link line 25. In response to the last-mentioned operation, the selector switch It and the line switchllll are released yin the usual manner. Thus, the connection extending to the control circuit 2) is` fully released andthe automatic switches utilized Ain completing the connection Vare conditioned yfor further use. At RA254, the relay-R250 opens a point in thev above-tracedcircuit for transmitting normal'tone signaling current by way of the link lineandprepares a circuit forv transmitting over this link 'line to the calling-substation signaling current which'will indicate by its reproductionthat the call'-forwarding'apparatus is conditionedfcr operation. AtiRA253, the relay '250 .prepares .a` circuit-forv transmitting to the substation: A signaling` current which,` when reproduced, will serve to inform a calling party at the substation 4A; that thecallv forwarding apparatus is conditioned torespond'to calls incomingY to. the. line." I).

With the apparatus'jin this' condition, if the subscriber for 'whose seryicesLthe'substation A is provided reirurnsto` this substation and initiates a call thereat; the 'lastementionedsignaling circuitA is'cornpleted,A so 'thatg'thefsubscriber is vin- 'formed'that the"callforwarding apparatus is conditioned for' operation and "may take lthe necessary steps: torelease thisv apparatus in the manner pointedout hereinafter. More particuiarly, the last-mentionedsignaling circuit is completed iInmediatevlythe: receivergprovided' at .the substationV A is. removed from, its Supporting .hook or. ,crad'lej this-circuit",extending from one terminal ofthe oi-normalf tone current source `by 'Way of C255, RA253,-`C|9'|,` thecondenser |14, RAI58',.RA|52, RAME, the 'upper'side of the kline ID, thel receiver provided at the,` substation A,the lower sideofV the line 10, the

winding of the line relay-embodied iin the line switch I3A and the'exchange battery to the opposite terminal of the ,oir-normal' -tone hcurrent source.

After the calll forwarding apparatus has been conditioned for operationin the mannerI justitransmit ringing currentover the'line'I' for the purpose of energizing Lthesignal` deviceprovided at'the` called' substation A. A 'portion of this ringing current' isi lay-passed'` through-'thewinding of the alternating current: relay 'R over ad circuit -whiclr may `partiallyl be traced as extending bygway of the upper conductor -of the line nIii, RAME, therepeater Winding |62, the

condenser |15, the'winding of R|5 IJ, the re-.- peater winding |6|, RA-Illl, and thelower line conductor of the line IIJ.` When energized over this circuit, the line relayrRIEiloperates to open, at RA|52, `theabove`traced circuit for transmitting oiT-normal Atone 'signaling cur-rent to the H' substation-1A. Ati RA|5|,;.theA relay- R150 lcompletes a circuit yextending by Waypf RA|148,

RA I 39 and `RAI 2 for' energizing fthe 'slow-to- -release relayRI'IG. 'The relayiRIlU, fupon operating, completes, at RAI I I, an obviousv holding circuit for itself. At RAI I2, therelay RI I0 completes la calling loop circuit including the .link line 2| and extending to the :line switch 22. This loop circuit may partially be traced as extending-by way of the upper conductor of the line 2|, the repeater winding y |63, the winding of `R|55, the repeater winding |64," RAII2, RA|3| and-the lower conductor of the link line l2|. In response to the completion of this-loop circuit, the line switch 22-"operates vto seize an idle one of the selector switches, such,for vexample, as the selector switch |6, to -which -it has access and to extend the -loop circuit thereto.

At RAI I3, the relay RI I0, upon operating,iopens theA previously traced operating circuit for the relay Rl and prepares a circuit Ifor energizing the relay RI |5. When'thewinding of the relay "RIDIJ is deenergized, the-weightedarmature |0| is released and starts vibrating alternately to engage its two associated contacts. Due to its slow-to-release characteristic, the relay RI05 is held in its operated' position untilv the vibratory movement of the armature -IQI is substantially ended. When the amplitude of vmovement of this armature is suiciently reduced so that it no longer engages its two associated contacts, the relay RISE is deenergized and restores. Upon restoring, therelay R||J5 opens,at-RA|06, the above-traced holding circuit for the relay RI I Il causing the last-mentionedrelay to restore afteran interval; provided ringing current s;not being transmittedoverthe line ID. At'RAIIlB, the` relay`R|05 completes 4the above-mentioned circuit for energizingthe `release-'magnet |88,

this circuit'extendingfrom groundv at `RA224 by way of C|98, RAI I3, RAIZLRA'IIJS, and the Winding ofthe magnet |88 to battery. The resulting operation of the release magnet causes thewiper of the digit sequence'switcl'il |85 to be returned to. its normal position. At RAI'I, the relay R|05, upon restoring, completes the previously mentionedcircuit for energizing the relay RI I5, this circuitextending fromv ground at, RA224cby way of. CI98, RA ||3, RAIIH and the winding of R||5y to battery. When `energized over this` circuit, the relay RI I5 attracts its weighted armature ||6 to complete a circuit extending by way of RAISGfor energizing the slow-to-release relay RI20. The relayRl2, upon operating, opensv at RA|2,|, the abovetraced circuit for energizing the release magnet` |88. `At RA|22, the relay R|20 short-circuits the operated armature RAI I2 of the relay 'RI I0, itbeing noted that the relay R operates prior to the release of the relay RI I8 in the, manner described above. At RAIZI, the relay R|2II opens a point in theabove-traced operating circuit for the relay'RIlU. ,At' RAIZZ', the relay RIZD completes an. obvouspcircuit forv energizing the Vibratoryrelay Rl33. The latter relay,

inturn, attracts its weighted armature to 4complete an obvious circuit, for energizing the slowto-release relay RI38. ,The relay R|38, upon operating, opens, at RA|39, a further point in the above-traced operating circuit .for the relay RIID. Thus, the relay RIIU is prevented from reoperating in response to operation of .the relay R|5 during the interval when the call isbeing forwarded to the substation B and for a predetermined time interval thereafter. 'In this regard, it will be understood that the relay R|58 operates each time a splash of ringing current is transmitted over the line I8. During the interval when the relay Rl I is operated, the successive operations of the relay R|58 are without effect aside from the completion of a multiple circuit for energizing the first-mentioned relay. After the relay R||8 is released, following cpleration of the relays R|28 and R|38, the operation of the relay R|58 is obviously without eiect. The relay RI I0, upon restoring, recompletes, at RA||3,the previously traced operating circuit for the relay RIDU causing the latter relay to attract its weighted armature |8| and thereby complete the operating circuit for the relay R|85. The relay R|85, upon reoperating, reprepares, at RAIDS, the holding circuit for the relay RIIU, interrupts at RA|81 the operating circuit for the relay RI I and opens, at RA|88, a point in the previously traced circuit for energizing the release magnet |88. When the re lay R||5 is deenergized in this manner, the weighted armature ||6 controlled thereby starts vibrating intermittently to complete the abovetraced operating circuit for the relay R|2|J. Due to its slow-to-release characteristic, however, the latter relay does not restore at this time.

The relay R|28, upon operating in the manner described above, also functions to initiate the operation of the register to transmit over the established calling loop circuit the impulses of the directory number designating the substal tion B to which the call is to be forwarded. More particularly, the relay R|28 opens, at RAI 23 and its associated resting contact, a point in theabove-traced operating circuit for the impulse sending relay R|25. At RA|23 and RAI24, the relay R|28 prepares a circuit, traced hereinafter, for energizing the slow-to-release relay RMD. weighted armature |26 controlled thereby is released and swings through its retracted position to engage its associated back contact and to release the armature |21 so that this latter armature also engages its back contact. In response to the latter operation, an alternative circuit is completed for energizing the winding of the relay R|25, this circuit extending from ground at RA224 by way of C|98, the armature |21 and the winding of R|25 to battery. In response to the completion of this lcircuit the weighted armature 26 is again attracted so that this armature is moved to its operated position to disengage its associated back contact and to move the ar-` mature |21 out of engagement with its associated .f-

resting contact. Thus, the alternative 'circuit for energizing the relay R|25 is interrupted. By virn tue of the completion of this alternative circuit. upon each back stroke of the weighted armature |26, this armature and the armature |21 are vibrated between two positions until a holding circuit for the relay R|25 is subsequently completed. Each time the armature |28` engages its associated back contact, a circuit is completed for energizing the pulsing relay R|38, this cir- When the relay R|25 is deenergized, the

obvious circuit for Ienergizing the relay R|35 in series with the operating magnet |82. The relay R|35 operates at the beginning of the first impulse transmitted through operation of the pulsing relay R|38 and, due toits slow-to-release characteristic, remains operated until the digit of impulses is ended. Upon operating, the relay R|35 prepares, at RAI 38, a holding circuit for the relay RMU; prepares, at RAIB, a circuit for energizing the operating magnet |81 and prepares, at RAI31, a circuit for energizing the release magnet |83. At RA|35, the relay R|35 completes an obvious alternative circuit for energizing the relay R||5, which latter relay is still vibrating intermittently to complete the operating circuit for the relay RIZU. When this alternative circuit is completed the relay R||5 holds its weighted armature I6 in the attracted position so that the operating circuit for the relay R|28 is not interrupted during impulsing. Each time the operating magnet |82 is energized by a currentvpulse transmitted thereto through operation of the pulsing relay R|38, it operates to advance the wiper |8| one step. Thus, the switch functions as an impulse counting switch for the purpose of determining the number of impulses transmitted during each digit. More particularly, when thewiper |8| is, duringits rst cycle of operation, operated into engagement with its associated third contact, the above-mentioned circuit is completed for energizing the relay RMI), this circuit extending from ground at RA224 by way of C198, RAl23, RAI24, the wiper |85, the wiper '|3 and its associated second contact, the third contact of the set associated with the wiper 8 the wiper |8| and the winding of RME) to battery. When energized over this circuit, the relay RME! opcrates to complete, at RAMI, an obvious circuit for maintaining the relay R|25 energized. Thus, the relay R|25 is held in its operated position so that the pulsing relay R|38 remains in its restored position and the impulses of the first digit are terminated. At RAMZ, the relay RM8, upon operating, completes ra holding circuit for itself, this holding circuit extendingfrom ground by way of RAIBB, RAMZ and the winding of RM8 to battery. At RAMA, the relay RMU completes a circuit for energizing the release magnet |83, this circuit extending from ground at RA|31 by way of RAM4 and the winding of the magnet |83 to battery. When energized over this circuit, the magnet |83 operates to cause the wiper |8| to be returned to its normal position, thus interrupting the above-traced operating circuit for the relay RMU. At RAM3, the relay RMU completes a circuit extending by way of RAI3B for energizing the operating magnet |81 of the digit sequence switch |85. When energized over this circuit, the magnet |81 operates to advance the wiper |88 one step sothat it is moved out of engagement with its associated first contact and into engagement with its associated second contact. Shortly followingv the operation of the relay RM8, the slow-to-release relay R|3t restores to open, at RA|36,'the hold-ing circuit for the relay RM8; to interrupt, atA RAISE', the operating circuit for the motor magnet |81; and to open, at RA|31, the circuit for energizing the release magnet |83. At RA|35", the relay,Rl35, upon restoring, also interrupts the above-mentio-ned alternative circuit for energizing the relay RI I5 with vthe result that this relay is deenergized and vibration of the weighted armature I6 controlled thereby is again initiated. Short- '1y following .the release;.of the:relayl R|3,5,ithe

.relay; R I d Il restores ftoz opent further ,points in 'its `holdingcircuit and the zoperatingfcircuits for zthemagnet |81 and the-release magnet |83. At RAIIII, the relay RIM) opens the holding; circuit for the relay RI25, whereby the periodic move- `ment of the weighted armature |26 carried by the latter relay is again initiated. Thus, the operation ofthe pulsing relay RI3 to transmit to the operated switch train the impulses of the* second digit is started. At the beginning of the rst impulse of this second digit `when the circuit for energizing the magnet |82 in*4 series with the relay RI35 is again completed, the relay RISE reoperates to again complete, atRAIS', the` alternative circuit for energizing .the relay RI I5. Accordingly, the weighted armature II6 controlled by the relay RI I is held in its attracted lposltion'to maintain the operating circuit for the relay RIZ!) completed. When the wiper II has been stepped two steps so that it stands in engagement with its associated second contact, an alternative circuit is completed for energizing the relay RMU, this circuit extending' by way of the grounded conductor CI98 RAI23, RAIN, the wiper |86 and its associated second contact, the wiper |12 and its associated second contact, the second Contact of the set associated with the wiper ISI, the wiper ISI and. the winding of RIM) to battery. 'The relay RIM), upon operating, again completes the holding circuit for the relayv R|25, thereby to arrest the operation of this relay and the pulsing relay RISI), and completes the previously traced operatingl circuits for theoperating magnet IB'I` andthe release magnet |83. 'As a result, the wiper ISI is returned to its normal position and the wiper |86 is advanced into engagement with its associated third contact. Shortly thereafter, the relays :RI35 and RIM) sequentially restore in the: manner explained above, the latter relay functioning to open, at RAMI, the holding circuit for the relay RI 25 so that vibratory` movement of the weighted armature vI2a` is again initiated. Thus, the operation of the pulsing relay RI3I! to transmit the impulses ofithe third digit of the directory number designating the substation B is started. During operation of thev pulsing relay to transmit these impulses, the wiper ISI is again advanced step 'by step at the rate of one step for eachrimpulse; it being understood that the relay RIS'CI reoperates at the beginning of the rst impulse of the digit to performthe functions previously described. When the wiper IBI is moved into engagement with its associated fourth Contact, corresponding to adigit of'. four impulses, a second alternative circuit is'completed for energizing the relay RIIIIJ, this circuit extending .by way of the grounded `conductor C|98, RAIZS, RAIZI., the wiper |86 and its associated third contact, the wiper I1 and its associated second contact, the fourth contact of the set associated with the wipery IIJI,` the wiper `IBI and the winding of RMD to battery. When energized over this circuit, the relay RIM again operates to complete, at RAIIlI, theholding circuit for the relayRI 25; thus terminating the vibratory movement or` this latter relayl andthe operation of the pulsing relay RISII. The relay RMI! also completes the previously traced circuits for energizing the release magnet |83 and the operating magnet |81, thus causing the wiper IBI to' be returned to its home position and thewiper |86 to be advanced into engagement with its'associatedfourthcontact. When `.`the `wiper: |86;v is'. stepped. into -engagement'fwith :rits iaassociated fourth z contact, fan alternative .holdingfcircuit is completed for the.: relay. R I 40, this circuit extending'by way of ithe grounded :conductor C193, RAIZS, RA|24the wiper |85 vaudits associated fourth contact, -RAIAZ and the windingof RMI) tobattery. Thus, the relay RIIHI.V is `preventedfrom releasing in Vresponse' to restoration of the relay RISE) whichloccurs shortly following the operation of the4 relay'RIIIElz at vthe end of thethirdV series of impulses. With the relay RMI) heldin its operated :position the impulse sending relay'RIZ is.` also energizedso that the pulsing. relay RISII `ismaintained 'in `its restored position. Thus, the transmission of impulses from the register equipmentl is terminated.

When the relay 'RISE restores shortly following the end of the third series of impulses transmittedr from the registerfequipment it opens;y at RAISE', the above-traced alternative circuit for energizing the -relayRI I5. Accordingly, vibration of the-weightedv armature IIBcon'trolled by the relay RI I5 isy again initiated. As explained above, the relay RI20, .duev to :its slow-to-release characteristic, does 'not restore until the. amplitude of movement of thearmature H6 is'suiiiciently reduced so` that this. armature'no longer engages either of its two associated contacts. The purpose of this arrangement is -to' provide an interval during whichthe called substation, as selected by the automatic switching apparatus in Aresponse to the :impulses vtransmitted thereto from the register equipment, may be signaled and the call answered. .1 In thisregard, it will beapparent from the? preceding idescription that the selector switch .I6 seized Vby the, line switch' 22.responds to the impulses of. thefirst digit transmitted thereto from theregister equipmenty by operating to select'the.group of connector switchesV having access to the called line Il. During the interdigit -pause between the first and second digit, this selector switch` operates to select an idle one ofV the selected group of switches, such, -for example, as the connector switch I8, and to-extend the calling loop circuit to the last-mentioned switch. The connector switch I8, in turn, responds to the .impulses of the second andV thirddigits.by-operating in the manner previously. explained to select the line II to whichv the .call is -to be routed. If this line is busy at the timeit .-is 'thus selected, busy tone current is "returned'over'the calling loop circuit extending tothe repeater AII'I and a'portion thereof is repeated i'byy induction-to the loop circuit Aextending through the connector switch I9, the selector switch II and 'the line switch I5v to the calling substation C. '.'I'his signal is intermixedwithl the ring-back tone signal being transmitted to they calling subscriber, but may be sufficiently Ydiscernible '.-to inform'the calling party that 'the calledline is busy. 'In' the event the line` II to' which the cally is forwarded is idle at the time it is selected'bythe.connector switch I8, the'control .apparatus of'. this 'ccnnector switch functions inthe manner. previously explained to transmit ringing current' over the line II for the purpose of energizing the signal device provided 'at the substation'B. .The dei sired.- conversational circuit vbetween the substations B and C is completed when4 the call is answered at the substation B. More particularly, when ythereceiver provided at the lastrmentionedgsubstation isgremovedrfrom its sup- )portingA hook or cradle, the usual zdirect current bridge is connected across the conductors of thel line 11 so that the ring cut-off and back bridge relays embodied in the connector switch 18 `sequentially operate. The back bridge relay, upon operating, functions to reverse the direction of .current flow over the loop circuit extending to the repeater 100 with the result that the polarized relay R155 operates. Upon operating, the relay R155 completes, at RA158, an obvious path shunting the operated armaturerRAlZZ, thereby to maintain intact the loop circuit extending through the line switch 22 when the relay R120 is subsequently released. At RA15'1, the relay R155 completes an obvious path for short-circuiting the condenser 115, thus establishing a direct current bridge across the conductors of the line 10. ring cut-off and back bridge relays embodied in the connector switch 19 are caused to operate in the usual manner. The ring cut-off relay of this connector switch, upon operating, arrests the ringing operation being performed by the switch, terminates the ring-back signal being transmitted to the calling substation C, and completes the desired conversational circuit between the substations B and C. When the ringing operation of the connector switch is ended, the intermittent operation of the relay R150 is terminated and this relay remains in its restored position.

The back bridge relay R155, upon operating, also functions to interrupt, at RA150, the previously traced operating circuit for the slow-torelease relay R120. At RA158, the relay R155, upon operating, opens a point in the previously traced circuit for transmitting off-normal tone signal current over the line 10. When the relay R120 restores it functions to reprepare, at RA121, the operating circuit for the relay R1 10 and to reprepare, at RA121, the above-traced operating circuit for the release magnet 188. At RA122', the relay R120 opens the operating circuit for the relay R133, thereby to cause the sequential restoration of the last-mentioned relay and the relay R138. At RA122, the relay R120 opens the path shunting the operated armature RA158. At RA123 and its associated resting contact, the relay R120 recompletes the previously traced multiple holding circuit for the impulse sending relay R125. At RA123 and RA124, the relay R120 interrupts the above-traced alternative holding circuit for the relay R140, causing the latter relay to restore after an interval. Upon restoring, the relay R150 opens, at RA141, the multiple holding circuit for the impulse sending relay R125. Following the release of the relays R150, R120, R133, R140 and R138, in the manner just explained, no further operation of the call forwarding apparatus occurs until the connection is released.

The manner in which the operated switches 15, 11 and 19 are released when the connection is cleared out at the calling substation C is exactly the same as described previously with reference to the call originating at the substation A. When the connection is cleared out at the substation B, the back bridge relay embodied in the connector switch 18 functions to again reverse the direction of current flow over the loop circuit extending tothe repeater160. Accordingly, the polarized back bridge relay R155 restores to interrupt, at RA158, the loop circuit extending through the switches 22 and 16 to the connector switch 18. When this loop circuit is interrupted the operated switches 18, 16 and 22 In response to this operation, the

are released in the order named and in the exact manner described previously with reference to the call originating at the substation A. At RA15'1, the relay R155, upon restoring, interrupts the path short-circuiting the condenser 115. At RA156, the relay R155 reprepares the operating circuit for the relay R120. At RA158', the relay R155 reprepares the circuit for transmitting offnormal tone signal current over the line 10. Following the release of the relay R155, the call forwarding apparatusr is full'y restored to normal and is conditioned to respond to another call routed to the line 10. In thisy regard, it will be noted that the relays R145, R125, R and R105 are maintained in their respective operated positions after the connection as routed to the substation B through operation of the call forwarding apparatus is released. It will further be noted that the digit sequence switch 185 is not restored to normal during the release of the call forwarding apparatus. When, however, another call is routed to the line 10 to cause the sequential operation of the relays R150 and R110, in the manner explained above, the previously traced circuit for energizing the release magnet 188 is completed immediately the relay R110 operates. Thus, the digit sequence'switch 185 is released during the initial response of the call forwarding apparatus in its operation to perform r a call forwarding operation.

If the above-described call, initiated at the substation Cv and intendedfor the substation A, is abandoned during the interval when the call forwarding apparatus is operating to route a l connection from the line 10 to the substation B,

this apparatus continues its operation even though the connection as set up between the substation C and the line 10 is released. Under such conditions, if the call is answered at the substation B during the interval which elapses between the `release of the relay R and the release of the relay R120, the back bridge relay R155 is caused to operate and a connection is fully completed between the repeating coil 100 and the telephone provided at the substation B. When the answering party challenges the connection and fails to obtain a response from the calling party, he is informed that the call has been abandoned and may initiate the release of the switch train through which the connection is routed from the repeating coil 100 to the line 1-1 by hanging up, thereby to cause the release of the back bridge relay R155 in the manner pointed out above. When this relay restores, the calling loop circuit extending from the repeating coil to the operated connector switch of the train is interrupted and the switches included in the train are restored to normal in the abovedescribed manner.

As indicated previously, the call as routed from the substation C to the. substation A may be answered at the last-mentioned substation even though the call forwarding apparatus is conditioned for operation. In such case, when the receiver provided at the substation A is removed from its supporting hook or cradle, a direct current bridge is connected across the conductors `of the line 10 to arrest the ringing operation being performed by the connector switch through which the connection extends and thus prevents further operation of the alternating current relay R150. When the call is answered in this manner, the previously traced circuit is completed for conducting the off-normal tone signal current through the receiver provided at the substation A, so that the answering` party is informed. that; thecallforwarding apparatus is conditioned for` operation. In the case under. consideration,

operation` ofj this apparatus is initiated, when.

ringing current is first transmitted over the line ||l and this apparatus operates to forward the connection tothe substationY B, or to another. substation designatedby the setting of the line` selecting switch |65. Assuming thatA the call is answeredV at the last-mentioned substation, a three-way talking circuit is established between thesubstations A` and C and thethird substationto which the call is forwarded. The completion of this three-way talking circuit in no Way prevents the release. of the twov operated switch trains when the conversation is termihated andthe three parties hang The arrangement is suchrthat if the abovedescribed call initiatedat the substation C is not,

abandoned by the calling party andthe call as forwarded through operation of the call forwarding` apparatus tothesubstation B.. is not answered during the interval which elapsesbetween thewrelease of the relay RI ISand the release of the, relay vRi 2li, the connection through which the callis forwarded to the substation B is released and a secondcycle ofoperation ofthe califorwarding apparatus isinitiated so thatr asecond connection is routed to the line II, Thus, when the transmission of impulses, to Vthe automatic switching apparatus of theI exchangeis ended, the .relay RI |51is deenergized in thev manner pre.- viously described so thatvibrationiof its. asso.- ciated armature IIS is initiated. When the ainplitude of vibration lof this armature is suilciently reduced `so that it no longer engageseither of its two associated contacts, the. operating circuit forthe relay R|20is interrupted. Upon restoring, the relay |Zreprepares,.at1RA|2|, theoperating circuit for the relay RI mand, at RAIZI,

the operating circuit for the release magnet |88.

At RA! 22, theA relay RI 2Q interrupts the, loop ,circuit Aextending by way ofthe-,linkline 2'I andv through the line switch 22- and theselector switch |6 to the connector switch v|8 therebyto initiate` thev release of these three switches. AtRAIZS and RAIM, thek relay Rl2openslthe. previouslytracedV alternative holding circuit, fortliet relay,

RMB@ causing the last-,mentionedrelay-to restore. At RA|23 `and its associated resting, con.-

tact, the relay RiZil completesthe previously,

traced holding circuit forthe relay R|25; At RAIZZ', the relay RIM-opens" the operating circuit-for the relay RIS3. When the relay-Rl33is deenergized, its weighted armature I3@ is released and starts vibrating alternately to engage,

armature |34 vibrates to hold. the relay R|35 operated is sufficient to insure the full releaseof the switch train through which the connection is forwarded to the substation, B. When the relayRlS finally restores it further prepares, at

RAISVQ, the operating circuit for the relay Rl l0..

Thereafter and during the next period when ringing current is transmitted over the line: Ii).

to cause the operation of the relay RISS, the operating circuit for the relay R| lil isA again com pleted.` The relay R| IB, upon operating, recom-- pletes its holding circuit, vrecornpletes thev loop circuit extending to the line switchv 22 and. interruptsthe operating circuit for the relay Rl 00. At

RAI I3, therelay RMB; completes the. previously.; traced circuit for energizing the. release:magnet1 |88, wherebythe wiper |86. ofthel switch is; returned to itshorne position., From, this pointon, the manner in which the call3forwarding apparatusoperatestoagain route a connection t0. the line is exactly the Same-as described previously. From the foregoing explanation it will be apparent; that the call forwarding apparatus functions repeatedly to forward a call through, the automatic switching apparatus of the ex.-` change to the substationdesignatedbyl thesetting ofthe line selecting, switch'iluntil the `call isansweredat the'last-mentioned substation or is abandoned at the calling substation. Inthis regard, it will be apparent that if a call-as for-` warded to the substationrB, for example,lis not answered at this substationand the `call is abancloned at thercallingsubstation, the lcall forwarding* apparatus willA belreleased and conditioned for f furtheroperation in response to zthe operation of the. relay. Rel-I5 to interrupt the operatingI circuit for thevrelay R420, andthus, cause the. sequential release` ofthe .relays R|2!lf, RI 33, RMU- and-:Rlin the mannery described above.

Inorder torender the-.call forwarding apparatus. nonresponsive toicalls routedto .the lineV i0, itfis necessary that a second. connection be.- routedto the control circuit Zland .then released.. For example, if the subscriber for whose, service the substation A is provided .returns to, this. substation and attempts to .initiate av call,v heis informed by. the off-normal tonesignal reproducedl by the .receiver provided at thisfsubstation and transmittedto theA substation over the circuit. previously `traced that thecall .for -forwardingap-` paratus is conditioned for. operation. Upon receipt ofthe. off-normal tone signal, the subscriber may cause a connection to be, forwarded tothe control circuit 2|) ,by dialingthesingle digitv required to cause one of the selector switches toseize `this circuit. Assuming, for example.,- that the` connection is .routed through the line. switch.

I3 and the selector switch I6,.when,the selector.A

RAE the pathA for connectingthecontrol conductor of `the link lineto ground, thereby tomaintaintheselector switch. I6 operated. When theY control circuit ZELfis4 seized the: above-traced: circuit .is completed for transmitting signal 'current to .the-calling substation.` In the,v present casa,- with the relay.Rinoperated, this circuit is en-.

ergized -bythe oir-normal tone-current, thereby tofindicate that the call Aforwarding.apparatus, is conditioned for. operation.; At,RA2I2,. the. relay R2 i recompletes the, operating circuit for the` slow-to-release hold relay Rth-and.. interruptsy the. previously traced. .path Yshoitt-circuting the windingof the relay 12.258,. When. this path is interrupted, the twoA relays ,R250`and R26v0are. energized in series over a Y circuit extending.: from` ground by way .ofI the off--n cri;r lal,springs.||9,`

RA252,Y the winding of Randthe winding ofA R25|l`to battery. The relay lILremainsl operated so long. as it .isenergized over, this circuit., When this circuit is completed, the relay.R,26|1

operates to openat RA2,|,.a point in4 the ,operatingv circuit for the relayRQndapoint in, the. above-traced short-circuitingpath, AtA R,A2|i,2.

the relay R250 opens .anpoint inMthe.previously tracedholding. circuit for, the nrelay .32.23;

When .the connection as .routed from, theA suhi station A to the control circuit 2|] is released, the

' and line switch I3.

line relay R210 restores to disconnect the control Y conductor of the link line 25 from ground and thus initiate the release of the selector switch 16 At RA212, the relay R210 interrupts the operating circuit for the hold relay R220, causing the last-mentioned relay to restore after an interval. Upon restoring, the relay R220 interrupts, at RA223, the previously traced operating circuit for the relay R145, causing the latter relay to restore and disconnect the repeater 160 from the conductors of the line 10. At RA224, the relay R220 disconnects the release conductor C198 from ground, thereby to deenergize the relays R100 and R125 and to open a point in the operating circuit for the pulsing relay R130. The relay R100, at its armature 101, interrupts, after an interval, the operating circuit for the relay R105. Thus, all of the relays illustrated in Fig. 1 are restored to normal. At RA222, the relay R220, upon restoring, completes an alternative circuit for energizing the operating magnet 116 of the line selecting switch 165. This circuit extends from ground at RA212 by way of RA222, C153, the olf-normal springs 118, the armature 111 and the Winding of the magnet 116 to battery. Due to the 'circuit interrupting action of the contacts associated with the armature 111, the magnet operates buzzer fashion and in cooperation with its associated ratchet and pawl mechanism functions to drive the wipers 111 to 113, inclusive, back to the normal position. When these wipers are returned to normal, the off-normal springs 118 are disengaged to open the above-traced alternative circuit for energizing the magnet 116, thereby to arrest the stepping operation of the Wipers. When the indicated wipers are returned to normal, the off-normal springs 119 are also moved out of engagement to interrupt the previously traced operating circuit for the relay R230 and the above-traced circuit serially including the windings of the two relays R250 and R260. Thus, all of the relays included in the control circuit are released and this circuit is conditioned for seizure in response to another connection routed thereto. After the wipers of the switch 105 have been returned to normal, the call forwarding apparatus is fully released and, since the repeater 160 is no longer connected to the conductors of the line 10, is nonresponsive to calls incoming to this line.

The apparatus illustrated in Fig. 3 of the drawings is adapted to be used in lieu of the control circuit 20 for the purpose of controlling the call forwarding apparatus illustrated in Fig. l. More particularly, this -apparatus comprises an auxiliary line 301 which is adapted to extend between a substation, such, for example, as the substation A, arranged for call forwarding service, and the call forwarding apparatus provided in the central exchange in association with the line extending to the substation arranged for call forwarding service. The apparatus further comprises an auxiliary impulsing device 300 and a start key 305 both of which are provided at the substation. In the central exchange the auxiliary line 301 terminates at the windings of the line relay R310 which is arranged to control a slow-acting hold relay R320. In order to adapt the apparatus shown in Fig. 3 for use in conjunction with the call forwarding apparatus illustrated in Fig. l, when the latter apparatus is connected to serve the substation A, the auxiliary impulsing device 300 and the startkey 305 are conveniently installed at the substation A in any desired manner. The line .301 is connected between this substation and the call forwarding apparatus, and the relays R310 and R320 are convenientlyassembled with the other elements of the call forwarding apparatus located in the central exchange. In the Central exchange the terminals .191 to 194, respectively, are connected to the terminals 330 to 333. The control circuit 20, including the off-normal springs 119 forming a part of the line selecting switch 165, may thus be dispensed with. Further, the above-described signaling circuit, provided for the transmission of off-normal tone signal current over the line 10, is no longer required and may be omitted from the apparatus since the position of the key 305, which is of the locking type, serves visually to indicate whether or not the call forwarding apparatus is conditioned for operation.

With the apparatus illustrated in Fig. 3 substituted for the control circuit 20 in the manner described in the preceding paragraph, if the subscriber for whose service the substation A isprovided desires to condition the call forwarding apparatus to respond to calls incoming to the line 10, he may do so by operating the key 305 to its off-normal position and operating the calling device 300 in accordance with the numerical value of the digit designating the substation to which the calls incoming to the line 10 are to be forwarded. When the springs of the key 305 are moved into engagement, through operation of this key to its off-normal position, an obvious circuit including the conductors of the line 301 and extending by way of the pulsing springs embodied in the calling device 300 is completed for energizing the line relay R310. The relay R310, upon operating, opens, at RA31 1 and its associated resting contact, a point in the circuit traced hereinafter for energizing the magnet 11.6 during the release of the call forwarding apparatus. At RA311 and its associated working contact, the relay R310 completes an obvious circuit for energizingthe slow-to-release hold relay R320. The relay R320, upon operating, opens, at RA321 and its associated resting contact, a further point in the circuit for energizing the magnet 116 during the release of the apparatus. At RA321 and its associated working contact, the relay R320 prepares a circuit for transmitting impulses to l this magnet for the purpose of operating the switch 165 to the position corresponding to the substation to which calls are to be forwarded. At RA322, the relay R320 completes a circuit ex'- tending by way of the terminals 330 and 191 for energizing the relay R145, causing the latter relayk to operate and prepare the previously traced circuit for energizing the relay R1 10 and connect the repeater 160 to the conductors of the line 10. At RA323, the relay R320 completes circuits commonly extending by way of the terminals 331 and |92, and substantially coincident with those previously traced, for energizing the relays R10!) and R125, whereby these two relays and the relay R are caused to operate. Following the operation of the relays R310, R320, R145, R100, R105 and R125, in the manner just explained and during operation of the calling device 300, the relay R310 is caused alternately to restore and operate a number of times determined by the numerical value of the digit dialed. Each time the relay R310 restores it opens, at RA31 1 ,the operating circuit for the relay R320 and completes the above-mentioned circuit for energizing the magnet 116, this circuit extending from ground by `way of RA3|'|, RASZI, lthe 'terminals '33"3 and 191| and the winding of the magnet |76 ito battery. "Obviously, this circuit is vinterrupted and the operating `circ-uit .for the relay R32-) is recom'pleted 'each -time 'the relay RSM! reoperates lai'fth'e end of the open circuit period of `an impulse Vtransmitted thereto. Due to its slow-to-release characteristid'the relay R320 remains operated during impulsing. Each time the magnet |16 is energized and deenergized vit functions in -cooperation with its associated ratchet and -pawl 'mechanism to advance the wipersf-H to |73, -in- 'olusive, 'one-step. yAt the end of the digit, therefore, lthese wipers are -left standing in engage- -ment 'with the contacts -corresponding to the vnumerical value of the digitand also to the substation to which calls are to-be forwarded. At the end of the digit the line Irelay RSI-'0 is held energized over the loop circuit including the line 30| so `that this relay and the relay 'R328 are Iheld in 'their respective operated positions -until 'the key v305 is returned to its `normal position.

--fter vthe wipers of `the switch |65 have been po'sitioned in engagement with the-contacts cor- 'responding to -the substation to which calls `are y :to be forwarded, this apparatus responds to calls incoming-to the line P3 by ioperating to cause vthe lcalls -to be forwarded to 'the `desired substation vin the exact manner described Apreviously with reference to `the arrangement including'the control circuit "2o. `In order to-re'nder the `call Aforwarding apparatus l'nonresponsive to calls routed to the line it, it is only necessary to restore the key S05-to its normal position. When the 'springs of this key 'are disengaged, the -loop Acircuit including the windings of the line relay .R310 'is `interrupted land this vrelay restores to open the operating circuit for the hold relay Rte. The last-mentioned relay, upon restoring, completes, at`RA3`2l, the above-traced circuit Afor causing the wipers of the switch |65 to be re- `turned to normal. This circuit extends from 'ground at RA3| by Vway of RA32I, the terminals '332 and |793, the ofi-normal springs |78, the Yar- :mature 17| l andthe winding o'f the magnet I1-6 `to battery. Due to the circuit interrupting action 'of the contacts associated 'with the Yarmature `||-`|,'fthe -magnet V56 incooperation with its associated ratchet and pawl mechanism,op`erates to 'return the Wipers l'l to |13, inclusive, to normal i -at which timethe springs iV3 are disengaged to interrupt 'the above-traced urelease' circuit and thus -arrestthe stepping operation of the wipers. Upon restoring, the lrelay vR320 also opens, at lRA3'22, the above-traced circuit for energizing therela-y RME, causing the latter relay to restore fanddisconnect thewindings of the 'repeater |76!) from across the conductors 'of the line It. At 4"r'tA3`23, the relay R323 opens the above-traced operating circuits 'for 'the relays YRi' and 'RES,

causinglb'oth of these relaysfto restore. The relay RTM, after an interval, opens the operating cir- `cuit for the relay Rl5, causing the last-men- V"tion'ed relay to restore. Thus, -the call forwardingapparatus 'is fully restored to normal yand'is;

rendered nonresponsive to calls routed through L'the automatic `switching apparatus of the exchange to the line Il).

'While there has vbeen described what are at present considered to be the `preferred embodilments'of the invention, it will be understood that `various modifications may be made therein, fand it is contemplated .to .cover in ythe :appended 'claims :all such modifications as fall within 'the true spiritiand'scopeofthe invention.

enrayer) y Whatis claimed is:

11.1In an automatic telephone system, `an 'eX- change, a plurality of subscribers lines extending to said exchange, said exchange comprisingautomatic switching apparatus for setting up connections between said lines, call forwarding apparatus in said exchange, said call forwarding appalratus being operative to forward calls incoming to one of said lines through said automatic 'switching apparatus lto any one of several other lines of Ythe system, a relay adapted to be conlnecte'd Vto vsaid one line to respond to ringing current transmitted over said one line and operative to initiate the operation of said call forwarding apparatus, and means vcontrollable over said one line for connecting said relay to said line.

2. DIn an automatic telephone system, an exchange, a plurality of subscribers lines extending to said exchange, said exchange comprising automatic switching apparatus for setting up connections between said lines, call forwarding apparatus in said exchange, said call forwarding apparatus 'including a register operative directively lto control said automatic switching lap- `paratus -to extend a connection from one of said "lines to any selected one of a number of the other lines, a relay adapted to be connected to said-one line to respond to ringing current transmitted over said'one line andoperative to initiate the operation of said call forwarding apparatus, and -means controllable over said one line for 4controlling said register t'o select the one of said other lines to which calls are to be forwarded Aand for connecting said relay to said one line.

3. In a telephone system, a subscribers line, other lines, a register, automatic means controllable over any line of the system for variably -setting said register in accordance with the directory designation of another of said lines, and means operative when a call is directed to said subscribers line under the condition of the register beingset, for causing said 'call to be routed tothe one of said other lines ycorresponding to the-setting of said register.

i:4.1m a telephone system, a -subscribers line, Iother lines, a register, automatic means control- Alable over said subscribers line and operative in response v.to a single digit-of impulses transmitted -thereto for 'variably setting said register in ac- Lcordance with the directory designation of any one of a plurality of said other lines, and means operative when a call is `directed to said sub- Ascribers line under the condition of the register being set, for causing 'said call to be routed to the one of said other lines corresponding to the setting of saidregister.

5. `Ln a telephone system, a subscribers line, Sotherlines, a register, automaticmeans controllable over -iany line of the system and operative in response to a single digit of impulses trans- ,mitted thereto for -variably setting said register .ina'ccordance .with the directory designation of lanother of said lines, and means operative when .'a call is directed to said subscribers line under :the condition of the register being set, for causing said call to be lrouted to the one of said other lines corresponding to the setting of said register.

i6. vIn -an automatic telephone system, a plufrality'of subscribers lines, automatic switching apparatus for setting up connections between said lines, call forwarding apparatus associated -with one of said lines, said call forwarding apparatus being operative to fior-ward calls `incomlines of the system, means for initiating the operation' of said call forwarding apparatus, and means controllable over any line of the system for conditioning said last-named means to operate in response to a call routed to said one line.

7. In an automatic telephone system, a plurality of subscribers lines, automatic switching apparatus for setting up connections between said lines, call forwarding apparatus associated with one of said lines, said call forwarding apparatus including a register operative directivelyto control said automatic switching apparatus to eX- tend a connection from said one line through said automatic switching apparatus to any selected one of a number of the other lines, means for initiating the operation of said call forwarding apparatus, and means controllable over any line of the system for controlling said register to select the one of said other lines to which calls are to be forwarded and for conditioning said last-named means to operate in response to a call routed to said one line.

8. In an automatic telephone system, a plurality of subscribers lines, automatic switching apparatus for setting up connections between said lines, call forwarding apparatus individual "to one of said lines and operative to forward calls lincoming to said one line to another of said lines, a circuit for controlling said call forwarding apparatus, said automatic switching apparatus including a selector switch having access to said circuitthrough its outlet contacts, whereof said lines and operative to forward calls incoming to said one line to another of said lines, a circuit for controlling said call forwarding apparatus, said automatic switching apparatus including a selector switch having access to said circuit, whereby said circuit is controllable over any line of the system, said circuit comprising means controllable over a connection including one of said lines and extending through said selector switch for conditioning said call forwarding apparatus to operate in response to a call routed to said one line, and means responsive to seizure of said circuit by said switch for transmitting a signal over said connection to the calling end thereof.

l0. In an automatic telephone system, a plurality of subscribers lines, automatic switching apparatus for setting up connections between said lines, call forwarding apparatus associated with one of said lines and operative to forward calls incoming to said one line to another of said lines, a circuit for controlling said call forwarding apparatus, said automatic switching apparatus including a selector switch having access to said circuit, whereby said circuit is controllable over any line of the system, said circuit compriisng means controllable over a connection including one of said lines and extending through said selector switch for conditioning said call forwarding apparatus to operate in response to a call routed to said one line, and means operative in response to the release of a connection routed through said switch to said circuit following the release of said last-mentioned connection for rendering said call forwarding apparatus `nonresponsive to calls routed to said one line.

11. In an automatic telephone system, a plurality of subscribers lines, automatic switching apparatus for setting up connections between said lines, call forwarding apparatus associated with one of said lines and operative to forward calls incoming to said one line to another of said lines, a circuit for controlling said call forwarding apparatus, said automatic switching apparatus including a selector switch having access to said circuit, whereby said circuit is controllable over any line of the system, said circuit comprising means controllable over a connection including one of said lines and extending through said selector switch for conditioning said call forwarding apparatus to operate in response to a call routed to said one line, means operative in response to the release of a connection routed through said switch to said circuit following the release of said last-mentioned connection for rendering said call forwarding apparatus nonresponsive to calls routed to said one line, and means responsive to seizure of said circuit by said switch for transmitting one signal over the connection routed through said switch in the event said call forwarding apparatus is conditioned to respond to calls routed to said one line and for transmitting a different signal over said lastmentioned connection in the event said call forwarding apparatus is not conditioned to respond to calls routed to said one line.

12. In an automatic telephone system, a plurality of subscribers lines, automatic switching apparatus for setting up connections between said lines, call forwarding apparatus associated with one of said lines and operative to forward calls incoming to said one line to another of said lines, a circuit fori controlling said call forwarding apparatus, said automatic switching apparatus including a selector switch having access to said circuit, whereby said circuit is controllable over any line of the system, said circuit comprising means controllable over a connection including one of said lines and extending through said selector switch for conditioning said call forwarding apparatus to operate in response to a call routed to said one line, means operative in response to the seizure of said circuit by said switch in'setting up a second connection to said circuit following the release of said last-mentioned connection for transmitting asignal over said second connection, and means operative in response to the release of said second connection tion routed thereto from any one of said lines for conditioning said call forwarding apparatus to forward calls incoming to a predetermined one of said lines to another of said lines, and means operative in response to the release of a second connection routed to said circuit from any one of said lines forrendering said call for- --warding apparatus nonresponsive to calls'incom- 4ing to said predetermined line.

14.-In an automatic telephone system, aplu- 'rality of subscribers lines, automatic'rswitching apparatus for setting up connections betweensaid lines, andvcall forwarding apparatus including a circuit accessible to certain of .theauto- -matic-switches'included in said automatic switchling apparatus, vsaid circuit including means operative in response to seizureithereof over a first connection routed thereto for conditioning said 'call vforwarding apparatus to forward calls in- -vcoming to one of said rlines to another of said lines, lmeans operative in response to the release of a :second connection routed to said circuit for rendering -said call forwarding apparatus non- `responsive tocalls'incoming `to said oneiine, andl means responsive to seizure of said circuit for transmitting one signal over the connection routed `tosaid circuit in the-event said call forl.

-warding apparatus is *conditionedv to respond to calls incoming to saidone `line and for transmitf ting a different signal over said last-named con- `nection in the event said call forwarding apparatus is not conditioned to respond to calls in-` coming to said one line.

115. In anautomatic telephone system, a plurality of subscribers lines, automatic switching apparatus for setting up connections between said`lines, call forwarding apparatus individual to -one of .said lines and including an impulse "sender for' directively controlling said automatic switching apparatus 'to forward calls incoming to said one line to aselected one of the other lines and an impulse responsive switch for selecting any one of said other lines and for controlling lthe operation of said impulse sender in accordance with the lineselected, control means operative to initiate vthe operation of said im- 'vpulse sender,` a circuit for controlling-said call 'forwarding' apparatus, said automatic switching apparatus including lmeans operative to establish Va connection between vsaid circuit and any'line ofthe system, said circuit including means for `'repeating-to-saidimpulse responsive switch impulses transmitted over said connection, thereby to cause saidswitch to -select the one of said other lines tovwhich calls routed to said one line are to be forwarded, and means for conditioning said control meansfto-operate fin response to a call rou-tedtosaid one line.

'116..1In.an` automatic telephone system, a plurality .ofvlsubscribers lines, automatic switching v,apparatusforisetting'up connections' between said llinesgzcallforwarding apparatus `individual to one -ofwsaidllines and including an` impulse sender for directively controlling said automatic switching apparatus'to' forward calls incomingfto said one line to-a'selected one of the other lines and an `impulse responsive switch for" selecting any one Hof; said other lines and for `controlling the operation; `of said impulse :sender accordance with the line-selected, -controlmeans operative to initiate the operationof said impulse senden-a 'circuit -for 4-controlling asaid. call forwarding i apparatus,f said automatic switching `apparatus including. means operative toaestablish a Vconnection between; said circuitand any line. of thefsysvtems-said: circuit .including meansfor `repeating to-said-impu'lse responsive switch'impulses transrlmittedoverfsaid connection, ,thereby to cause ',saidfswitch to selectzthexone of. "saidother lines toiwhich calls:routed'ftoisaid;oneline `are to be `forwardedV means kfor conditioning-said .control means to' operate in responseitoiatcall routed Yto said one' line, andmeans operative in response to the release of a'second connection routed Ato said circuit for releasing said impulse responsive switch and for rendering said control -means nonresponsive to calls routed to said lone line.

17. In an automatic telephone system comprising a plurality of subscribers lines andV automatic switching apparatus forsetting up'connections. between said lines,"call forwardingapparatus individual lto one .ofsaidlines and oper- I ative to forward calls incomingto said one'fline toianotlier selected line, said call forwardlyfapparatus comprisingy a switch controlled inl-'accordance with impulses transmittedV thereto overfany line of the system for selecting'the line'to which said calls areV to be forwarded,- :anr impulse :sender controlledA in accordance with the settingof said switchlforl transmitting to said automatic switching apparatusthe impulses of the directory number designating.the selected line, means operative in response toal call irouted to said one. linefor imitating the operation of saidsender,r` and means controllable over any line of the systemfforlreleasing said switch'and forv rendering `said lastnamed means nonresponsivelto calls routedzto said oneilline.

18.1111 an automatic -telephone `system comprising aplurality of subscribers lines and'automatic switching .apparatus for setting vup 4.connections `between said lines, call forwardingapparatusindividual=to one of said lines and operative` to Vforward calls .incoming toA said.l one line to another selected line, said call forwarding apparatus comprising a line selecting switch including a pluralityy of -sets fof` contacts individually .corresponding to rthe,` impulsedigits of directory numbers designatingsaid other lines, wipers-operative torengage cor-responding contacts of. said contact sets thereby to select the -digitsof the directory numbers designating --said other-lines, andmeans adapted to be controlled hin vaccordance with impulses transmitted .over any lineV of .the system for operatingsaidwipers -to v.engage the contacts corresponding .toa..line:.to which calls are. to be forwarded, an impulsesender for transmitting impulses to said automaticswitching apparatus, asending controlswitchoperative in response to operation of saidimpulse sender, a digit sequence switch, means controlled by apparatus including said sending control switch for controlling said sequence switchmto cause the operation thereof at the end of each digit of vimpulses transmitted by Ysaid. impulse sender, means including said. sending .control switch and said sequence switch for causing said sender to transmit to saidautomatic switching cluding a plurality of sets of kcontacts individually corresponding to the impulsedigits of directory numbers designating said other lines, wipersoperative to engage corresponding 4contacts'oLsaid contact sets thereby to select'the 'digits'ofithe directory numbers designating said other lines,

and means adapted to Vbe 'controlled in'accordance with impulses 'transmitted overany line of the system for operating said wipers tofengage the contacts corresponding to a line to 'which calls are to be forwarded, an impulse sender for transmitting impulses to said automatic switching apparatus, a sending control switch operative in response .to operation oi said impulsev sender, a digit sequence switch, means controlled by apparatus including said sending control switch for controlling said sequence switch to cause the operation thereof at the end of each digit of impulses transmitted by said impulse sender, means including said sending control switch `and said sequence switch for causing said sender to transmit to said automatic switching apparatus the impulses making up the digits of the directory number of the line to which calls are to be forwarded, a timing device, means operative in response to a call routed to said one line for initiating the operation of said timing device, and means controlled by said timing device for initiating the operation of said impulse sender a predetermined time interval after said call is routed to said one line.

20. In an automatic telephone system comprising a plurality of subscribers lines and automatic switching apparatus for setting up connections between said lines, a repeaterincluding a iirst winding adapted to be connected across the conductors of one of said lines and a second winding adapted to be included in a calling loop circuit extending to said automatic switching apparatus, call forwarding apparatus individual to said one line and operative to forward calls incoming to said one line to another vselected line, a switch adapted to be controlled in accordance with impulses transmitted thereto over any line of the system for selecting the line to which said calls are to be forwarded, means operative in response to said impulses for connecting said first winding across the conductors of said one line, an irnpulse sender controlled in accordance with the setting of said switch for transmitting over said calling loop circuit the impulses of the directory number designating the selected line, and means operative in response to a call routed to said one line for completing said calling loop circuit and for initiating the operation of said sender.

2l. In an automatic telephone system comprising a plurality of subscribers lines and automatic switching apparatus for setting up connections between said lines, a repeater including a rst winding adapted to be connected across the conductors of one of said lines and a second winding adapted to be included in a calling loop circuit extending to said automatic switching apparatus, call forwarding apparatus individual to said one line and operative to forward calls incoming to said one line to another selected line, a switch adapted to be controlled in accordance with impulses transmitted thereto over any line of the system for selecting the line to which said calls are to be forwarded, a timing device, means operative in response to said impulses for connecting said first winding across the conductors of said one line and for conditioning said timing device for operation, an impulse sender controlled in accordance with the setting of said switch for transmitting over said calling loop circuit the impulses of the directory number designating the selected line, means operative in response to a call routed to said one line for completing said calling loop circuit and for initiating the operation of said timing device, and means controlled by said timing device for initiating the operation of said 'sender-a1 predetermined timeintervalaftersaid l loop circuit iscompleted.

22.`5In1-automatic "fteleph'onesystem comprising awplurality -ofJsubscri-bersY llineslandv automatic switching apparatus'ifor-settingf. up connections betweenvv said lines, a 'repeater including-ifa -rst winding adapted' to be connectedacross-lthe conductors of one ofsaid lines andla secondwinding adapted to be included in a calling loop circuit extending to said automatic switching apv paratus, call forwarding apparatus individual to said one line and operative to forward calls incoming to said one line to another selected line, a line selecting switch including a plurality of sets of contacts individually corresponding to the impulse digits of directory numbers designating said other lines, wipers operative to engage corresponding contacts of said contact sets, thereby to select the digits of the directory numbers designating said other lines, and means adapted to be controlled in accordance with impulses transmitted over any line of the system for operating said wipers to engage the contacts corresponding f to the line to which calls are to be forwarded,

means operative in response to said impulses for connecting said rst winding across the conductors of said one line, an impulse sender for transmitting impulses over said calling loop circuit to said automatic switching apparatus, a sending control switch operative in response to operation of said impulse sender, a digit sequence switch, means controlled by said sender control switch for controlling said sequence switch to cause the operation thereof at theend of each digit of impulses transmitted by said sender, means including said sending control switch and said sequence switch for causing said sender to transmit over said calling loop circuit the impulses making up the digits of the directory number designating the line to which calls are to be forwarded, and means operative in response to a call routed to said one line for completing said calling loop circuit and for initiating the operation of said sender.

23. I n an automatic telephone system comprising a plurality of subscribers lines and automatic switching apparatus for setting up connections between said lines, a repeater including a rst winding adapted to be connected across the conductors of oneof said lines and a second winding adapted to be included in a calling loop circuit extending to said automatic switching apparatus, call forwarding apparatus individual to said one line and operative to forward calls incoming to said one line to another selected line,

a line selecting switch including a plurality of l timing device, means operative in response to saidv impulses for connecting said nrst winding across the conductors of said one line and for conditioning said timing device for operation, an impulse sender for transmitting impulses over said calling loop circuit to said automatic switching apparatus, a sending control switch operative in response to operation. i of said impulse sender, ar digit sequence switch, means controlled by said quence switch to cause the operation thereof at the end of each digit of impulses transmitted by said sender, means including said sending control switch and said sequence switch for causing said sender to transmit over said calling loop circuit the impulses making up the digits of the directory number designating the line to which calls 'sender control switch for controlling said seare to be forwarded, means operative in response to a call routed to said one line for completing said calling loop circuitand for initiating the op eration of said timing device, and means controlled by said timing device for initiating the operation of said sender a predetermined time interval after said loop circuit is completed.

JOHN WICKS.- 

